Wellbore tool with indexing mechanism and method

ABSTRACT

A wellbore tool, a wellbore fluid treatment string and a method with an indexing mechanism. The indexing mechanism can be shifted through one or more inactive positions before finally shifting into an active condition. The indexing mechanism is particularly useful with a plug that lands in a seat to impart an axially directed force on the mechanism before passing through the seat.

PRIORITY APPLICATION

This application claims priority to U.S. provisional application Ser.No. 61/703,131, filed Sep. 19, 2012.

FIELD OF THE INVENTION

The invention relates to a wellbore tool with an indexing mechanism andmethods for using the tool.

BACKGROUND OF THE INVENTION

If a wellbore tool is positioned down hole in advance of its requiredoperation, the tool must be actuated remotely. Indexing mechanisms maybe useful where a tool is intended to be actuated through a number ofpositions.

For example, in some tools, indexing mechanisms are employed to actuatea tool through a number of inactive positions before it reaches anactive position. For example, indexing mechanisms may be employed inwellbore tools for wellbore fluid treatment such as staged welltreatment. In staged well treatment, a wellbore treatment string isdeployed to create a plurality of isolated zones within a well. Thewellbore treatment string includes a plurality of openable ports thatallow selected access to each such isolated zone. The treatment stringis based on a tubing string and carries a plurality of packers that canbe set in the hole to create isolated zones therebetween about theannulus of the tubing string. Between at least selected packers, thereare openable ports through the tubing string. The ports are selectivelyopenable and include a sleeve thereover with a sealable seat formed inthe inner diameter of the sleeve. By launching a ball, the ball can sealagainst the seat and pressure can be increased behind the ball to drivethe sleeve through the tubing string to open the port in one zone. Theseat in each sleeve can be formed to accept a ball of a selecteddiameter but to allow balls of lower diameters to pass.

Unfortunately, due to size limitations with respect to the innerdiameter of wellbore tubulars (i.e. due to the inner diameter of thewell), such wellbore treatment systems may tend to be limited in thenumber of zones that may be accessed. For example, if the well diameterdictates that the largest sleeve in a well can at most accept a 3¾″ball, then the well treatment string will generally be limited toapproximately eleven sleeves and, therefore, can treat in only elevenstages.

A tool with an indexing mechanism may permit a ball of one size toactuate a number of tools and thus permit a string to be employed with agreater number of zones.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, there is providedwellbore tool that is actuable through a plurality of positionscomprising: a tubular housing including an upper end, a lower end, anaxis extending between the ends and a wall defined between an innersurface and an outer surface; a tool mechanism capable of beingreconfigured from a first inactive position to an active position; anindexing mechanism for reconfiguring the tool mechanism, the indexingmechanism including an indexing ring in the tubular housing, theindexing ring including an inner bore and being rotatably movable aboutthe axis, and an inner sleeve positioned within the tubular housing andextending through the inner bore, the inner sleeve having an axial boreextending therethrough and a wall thickness, and a plurality of pawlsforming a seat on the inner sleeve, each of the plurality of pawls beingpivotally connected to the inner sleeve and having an inner facingsurface open to and biased into the axial bore and a back side surfacepositioned for engagement with the indexing ring; and an actuator forpassing through the axial bore and contacting the inner facing surfacesto drive the plurality of pawls radially out into full meshingengagement with the indexing ring to thereby drive the indexing ring torotate and to move the tool mechanism from the first inactive positiontoward the active position.

In accordance with another aspect of the present invention, there isprovided a wellbore sliding sleeve sub comprising: a tubular housingincluding an upper end, a lower end, an axis extending through the upperend and the lower end and a wall defined between an inner surface and anouter surface; a port through the wall of the tubular housing; a sleevein the tubular housing, the sleeve having an inner bore and beingmoveable from a closed position overlying the port to an open positionexposing the port; a ball seat on the sleeve configurable between anexpandable form and non-expandable form, the ball seat including aplurality of pawls, each pawl having a front side surface exposed in theinner bore and a backside surface opposite the front side surface andeach pawl being pivotally connected to the sleeve through a fulcrumhaving an axis of rotation substantially parallel to the axis such thatthe pawls are rotationally moveable between a constricted positionprotruding into the inner bore and an expanded position having an innerdiameter greater than the constricted position; an indexing mechanismfor reconfiguring the ball seat from the inactive position to the activeposition, the indexing mechanism including a pawl protrusion on the backside surface of at least one pawl and an indexing ring with a pluralityof teeth on its inner facing surface, the plurality of teeth forming atleast one valley capable of meshing with the pawl protrusion, theindexing ring being rotatable relative to the sleeve and encircling thesleeve about the plurality of pawls, expansion of the plurality of pawlsfrom the constricted position to the expanded position driving meshingof the pawl protrusion with the at least one valley and rotation of theindexing ring to accommodate the meshing; and an actuator for passingthrough the inner bore and contacting the front side surfaces of theplurality of pawls to drive the pawls to the expanded position to forcethe pawl protrusion to mesh with the valley of the indexing ring andthereby to rotate the indexing ring relative to the sleeve toreconfigure the ball seat from the expandable form toward thenon-expandable form.

In accordance with another aspect of the present invention, there isprovided a method for actuating a downhole tool to an active position,the method comprising: passing an actuator through a expandable ballseat in the downhole tool to permit incremental movement of an indexingring about the ball seat until the indexing ring moves to a finalposition wherein the ball seat is held by the indexing ring againstexpanding and is capable of catching a sleeve shifting device.

It is to be understood that other aspects of the present invention willbecome readily apparent to those skilled in the art from the followingdetailed description, wherein various embodiments of the invention areshown and described by way of illustration. As will be realized, theinvention is capable for other and different embodiments and its severaldetails are capable of modification in various other respects, allwithout departing from the spirit and scope of the present invention.Accordingly the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings, several aspects of the present invention areillustrated by way of example, and not by way of limitation, in detailin the figures, wherein:

FIGS. 1 to 4 are views of a wellbore tool with an indexing mechanism,wherein:

FIG. 1 is a sectional view through a wellbore tool in a position readyto be moved through an indexing cycle;

FIG. 2 is an enlarged view of area A in FIG. 1;

FIG. 3A is an isometric view of a portion of an inner sleeve of thewellbore tool of FIG. 1. The portion of the sleeve is that portion belowline I-I of FIG. 1;

FIG. 3B is another isometric view of a portion of an inner sleeve of thewellbore tool of FIG. 1; and

FIGS. 4A and 4B, sometimes referred to collectively as FIG. 4, areenlarged end views of the portion of the sleeve of FIG. 3 showingsequential stages in the indexing cycle;

FIG. 5 is a sectional view through a wellbore having positioned thereina fluid treatment assembly and showing another method according to thepresent invention; and

FIGS. 6A to 6F, sometimes referred to collectively as FIG. 6, are aseries of schematic sectional views through a wellbore having positionedtherein a fluid treatment assembly showing a method according to thepresent invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

The description that follows and the embodiments described therein, areprovided by way of illustration of an example, or examples, ofparticular embodiments of the principles of various aspects of thepresent invention. These examples are provided for the purposes ofexplanation, and not of limitation, of those principles and of theinvention in its various aspects. In the description, similar parts aremarked throughout the specification and the drawings with the samerespective reference numerals. The drawings are not necessarily to scaleand in some instances proportions may have been exaggerated in ordermore clearly to depict certain features.

A wellbore tool that is actuable through a plurality of positions mayinclude a tubular housing including an upper end, a lower end, an axisextending between the ends and a wall defined between an inner surfaceand an outer surface; a tool mechanism capable of being reconfiguredfrom a first inactive position to an active position; an indexingmechanism for reconfiguring the tool mechanism, the indexing mechanismincluding an indexing ring in the tubular housing, the indexing ringincluding an inner bore and being rotatably movable about the axis, andan inner sleeve positioned within the tubular housing and extendingthrough the inner bore, the inner sleeve having an axial bore extendingtherethrough and a wall thickness, and a plurality of pawls forming aseat on the inner sleeve, each of the plurality of pawls being pivotallyconnected at one end to the inner sleeve and having an inner facingsurface open to and biased into the axial bore and a back side surfacepositioned for engagement with the indexing ring; and an actuator forpassing through the axial bore and contacting the inner facing surfacesto drive the plurality of pawls radially out into engagement with theindexing ring to drive the indexing ring to rotate and move the toolmechanism from the first inactive position toward the active position.

In operation, the tool may be employed in a wellbore operation whereinthe tool is positioned in a well with the housing in a selectedposition, a force may be applied to an indexing mechanism of the tool todrive a tool mechanism through a plurality of positions, the appliedforce may be via an actuator passing through the tool while it isinstalled downhole. The actuator may be launched from surface. Theactuator may be free to move through the wellbore toward and through thetool without connection to surface. Passing the actuator through theindexing mechanism permits incremental movement of the indexing ring totake the indexing mechanism through an indexing cycle. After one or moreactuators are passed through the tool, thereby moving the tool throughone or more indexing cycles, the indexing ring moves to a final positionwherein the tool is brought into an active position. The indexingmechanism includes the plurality of pawls protruding into the inner boreof the tool such that it can receive the applied force of the actuatorpassing therethrough. The plurality of pawls protrude into the innerbore of the tool, and define a constriction in the bore of the sleeve,the constriction having an inner diameter less than the outer diameterof the actuator used to operate the indexing mechanism. However, thepawls can be pushed radially outwardly (called opening or expandingherein) if sufficient force is applied, such expanding enlarges theinner diameter to be greater than the inner diameter in the constrictedposition and allows the actuator to pass. The indexing mechanism in oneembodiment, also includes an indexing ring that senses when the pawlshave expanded and can be set to allow a selected number of actuators topass before moving into a final position, wherein the pawls are nolonger capable of expanding. In one embodiment, the plurality of pawlstogether form a ball seat that in the final position is held againstexpanding radially outwardly. In this position, the ball seat is activeto catch a sleeve-shifting device to drive movement of the inner sleeve.

Generally, a wellbore tool often has a tubular housing, which, having atubular form, can pass readily through the wellbore as drilled. Also,tubular forms can be connected by threading into assembled tools orstrings deployable into a well. The tool may be run into a well fortemporary use or may be installed in a well for longer term use orreuse.

The wellbore tool may be a packer, an anchor, a sliding sleeve tool,etc. The form of the wellbore tool is determined by its tool mechanism.For example, a packer includes a tool mechanism including a packingmechanism with at least a set and an unset position, the packingmechanism may include an annular packing element, one or morecompression rings, etc. The tool mechanism of an anchor includes ananchoring mechanism including at least a set and an unset position, theanchoring mechanism may include a plurality of slips, a slip expander,etc. A tool mechanism of a sliding sleeve tool includes a port and asliding sleeve moveable to open and close the port. The sliding sleevetool has at least a closed port position and an open port position. Asanother example, another sliding sleeve tool has a tool mechanismincluding a port, a sliding sleeve moveable to open and close the portand a seat for the sliding sleeve to allow plug actuation of the slidingsleeve and in such an embodiment, the sliding sleeve valve may includeat least an activated seat position ready to catch a plug (such as aball or other plug form that is sized to seal in the seat) and aninactive seat position wherein either the seat has not yet formed or theseat is in place but is expandable such that the ball may pass throughthe seat.

The form of the tool determines the method that is carried out by thetool. For example, the method may include forming an annular seal,anchoring a tool, opening a port, etc.

The tools and methods of the present invention can be used in variousborehole conditions including open holes, cased holes, vertical holes,horizontal holes, straight holes or deviated holes.

With reference to FIGS. 1 to 4B, an example of a wellbore sliding sleevetool 10 is shown that is modified by the passage therethrough of one ormore actuators 11. The passage of the actuators eventually configures aninner sleeve 12 of the tool to be drivable to an open position by asleeve-shifting device 14. While inner sleeve 12 can originally beconfigured not to be shiftable, it can be modified by the passage of oneor more actuators to be shiftable. In particular, by passage ofactuators 11, sleeve 12 can be configured such that during thesubsequent passage of a sleeve-shifting device 14, sleeve 12 may beactuated by the sleeve-shifting device to shift open. Thereconfiguration of the sleeve to be driven by a sleeve-shifting devicein this embodiment, includes the formation of a seat 16 innon-expandable form (FIG. 4B) after one or more actuations of the tool,as controlled by an indexing mechanism. For example, in one embodiment,the indexing mechanism may allow the tool to be advanced through aplurality of positions where the seat is expandable, prior to placementinto a position wherein the seat is actually configured in anon-expandable way. As shown in the Figures, one or more actuators mayeach cycle the components of the indexing mechanism to advance oneposition, through one or more inactive (also termed passive) positions,before finally moving into an active position to form the final,non-expandable valve seat 16.

In the drawings, FIG. 1 shows tool 10 in a run in position just about tobe cycled by actuator 11, which in this embodiment is in the form of aball; FIG. 4A shows the tool in an inactive position, with the actuatorpassing through the tool and wherein the ball seat is fully expanded;and FIG. 4B shows tool 10 in an active position, with seat 16 formed ina non-expandable way to stop a sleeve shifting device 14. Thesleeve-shifting device 14 has not yet landed on the seat, but its outerdiameter can be seen. When the ball lands, the seat will expand radiallyout to some further degree to an unexpanded diameter IDu, but not enoughto allow the device to pass.

The illustrated sliding sleeve tool includes a tubular housing 20including an upper end 20 a, a lower end 20 b, an inner surface 20 cdefining an inner axial bore and an outer surface 20 d. Although notshown, the sliding sleeve tool, may be formed as a sub with its tubularhousing 20 having ends 20 a, 20 b threaded or otherwise formed such thatit may be connected into a wellbore tubular string. The housing definesa long axis x extending concentrically relative to inner surface 20 cthrough ends 20 a, 20 b.

The sliding sleeve tool includes one or more ports 22 through the wallof the tubular housing where the port, when opened, provides accessbetween the inner axial bore and outer surface 20 d. The open and closedcondition of port 22 is determined by sleeve 12. The sleeve is axiallymoveable in the tubular housing between a position overlying and closingport 22 (FIG. 1) and a position at least partially retracted from, andtherefore opening, port 22. In the open position in the embodiment,sleeve 12 would be moved to butt at its end 12 c against shoulder 20 e.

Sleeve 12 includes an inner bore 12 a and an outer facing surface 12 b.The sleeve includes seat 16 in bore 12 a. Seat 16 is the tool mechanismcapable of being configured through a plurality of positions includingone or more inactive positions and an active position. In the inactivepositions (FIGS. 1 and 4A) seat 16 is expandable and allows anyactuator, such as actuator 11, that lands therein to pass. In the activeposition (FIG. 4B), seat 16 is configured in a non-expandable way and iscapable of catching and retaining sleeve-shifting device 14. Inparticular, seat 16 in the active position cannot expand andsleeve-shifting device 14 that is sized to be larger than the unexpandedIDu of the seat will be caught in the seat and cannot pass through.Sleeve shifting device 14, therefore, lands in and creates a substantialseal with the seat. Thus, an axially directed force can be applied tosleeve 12 by fluid pressure through the piston effect created by device14 in seat 16. The applied pressure can overcome any holding devicessuch as shear pins 17 and drives the sleeve to open.

Sleeve shifting device 14 and actuators 11 may be plugs such as balls,as shown, or other plug forms like darts, etc., that are launchableuphole of the tool, such as from surface, and sized to have an outerdiameter greater than the unexpanded IDu of seat 16. The actuator 11 mayactually be identical to sleeve shifting device 14, but the seat expandswhen it is in an inactive configuration to let actuator 11 pass, whileseat 16, when active, is configured to retain and create a substantialseal with sleeve shifting device 14, which explains the differingoperations.

The indexing mechanism includes a plurality of pawls 24 and an indexingring 26. The pawls 24 protrude into the inner bore of sleeve 12 to sensethe passage of an actuator. Herein, pawls 24 also form seat 16. Thus,seat 16 is the tool mechanism and also part of the indexing mechanism.

Pawls 24 each include a base end 24 a, front side surface 24 b and abackside surface 24 c.

Pawls 24 are each connected at base end 24 a to sleeve 12 by a fulcrumpin 28, here in the form of shoulder bolts. Each fulcrum pin 28 connectsits pawl 24 such that the pawl pivots about an axis y, which follows thelength of the pin and is substantially parallel to axis x. Each pawl 24is connected by pin 28 in a slot 30 formed through the wall of sleeve 12such that, when pivoting, the front side surface 24 b is exposed and canprotrude into inner bore 12 a and back side surface 24 c is exposed onouter surface 12 b. Pawls 24, being exposed in the sleeve's bore 12 a,can be acted upon by structures passing through the sleeve's bore.

Pawls 24 are normally biased to protrude into the inner bore 12 a by aspring 31 such as in the form of a garter spring. The bias in spring 31can be overcome to cause the springs to expand.

The pawls are spaced apart about a circumference of sleeve 12 andeffectively create a ring coaxial with axis x. Pawls 24 are each asegment of a ring and, therefore, may each be arcuate along their lengthfrom their base ends 24 a to their outboard ends 24 d. As such, thepawls can have a concave curvature along their front side surfaces and aconvex curvature along their back side surfaces.

Each pawl has on its back side surface 24 c one or more pawl protrusions32, for example, a plurality of which may be formed as ratchet teeth.

Indexing ring 26 is positioned concentrically about the sleeve, alignedbehind pawls 24. Pawls 24, when expanding (i.e. moving radiallyoutwardly), can contact indexing ring 26. Ring 26 extends substantiallyconcentrically about slot 30.

Indexing ring 26 includes an inner bore with an inner facing surfacethat includes a plurality of teeth 34. Thus, indexing ring 26 has theform of an internally toothed gear ring. The plurality of teeth form atleast one valley 34 a between two adjacent teeth. Because there are manyteeth in the illustrated embodiment, there are many valleys 34 a. Teeth34 and the pawl protrusions are shaped so that pawl protrusions 32 onpawls 24 are capable of meshing into the valleys between adjacent teeth.Meshing of protrusions 32 into the valleys, as when pawls 24 expand,causes rotation of ring 26.

While indexing ring 26 is rotatable about sleeve 12, rotation of ring 26is limited to being in one direction only. In this illustratedembodiment, for example, ring 26 includes a second internal toothprofile 36 that interacts with a external toothed profile 38 on sleeve'souter facing surface 12 b. Alternately or in addition, teeth 34 may beasymmetrical, with each tooth flank having a moderate slope on one sideand a much steeper sloped flank on the other side so that rotation isurged in one direction over the other.

Teeth 36, 38 have a different profile than protrusions 32 and teeth 34,such that when teeth 36, 38 fully mesh, protrusions 32 are out ofalignment with the valleys between teeth 34 and vice versa. In theillustrated embodiment, teeth 36, 38 have a finer pitch than teeth 34.

Indexing ring 26 also includes a tab 42 extending from its edge. Whileindexing ring 26 can rotate about sleeve 12, rotation is stopped whentab 42 butts against a stop tab 44 on sleeve 12. While tab 42 can bepositioned to move along a gap 46 between ring 26 and sleeve 12, tab 42eventually is stopped against the stop tab 44 protruding from sleeve 12into gap 46.

In this embodiment, indexing ring 26 and sleeve 12 each have multi-partconstructions to facilitate assembly. Sleeve 12 includes a main sleevehaving an upper part 48 a and a lower part 48 b, with internal housings49, 50 secured therewithin on either side of pawls 24. Indexing ring 26includes an internally toothed ring 52 with teeth 34 and two rings 54,55 on either side of ring 52. One or both rings 54, 55 carry theinternal tooth profiles 36. Rings 54, 55 overlie the sleeve beyond endsof slot 30. Rings 52, 54, 55 are secured together to act as one ring asby use of interlocking keys 56. In addition, all parts of sleeve 12 andring 26 are connected to move together axially.

While the illustrated tool includes four pawls 24, more or fewer pawlscan be employed. However, there is some benefit in providing a pluralityof pawls substantially equally spaced apart about the sleeve'scircumference so that any forces on the pawls may be balanced about thecircumference and there may be a back up of pawls to overcome a failureof one pawl, since each pawl may operate independently.

Indexing ring 26 works with pawls 24 to index the tool through a numberof cycles of inactive positions before reaching the active position.Pawls 24 normally are biased inwardly to protrude into the sleeve'sinner bore 12 a. In particular, pawls 24 normally extend inwardlythrough slot 30 and define a constriction having an inner diameter IDuin the sleeve's inner bore. However, when pawls 24 are expanded (i.e.driven radially outwardly) as by an actuator 11 passing therethrough,backside 24 c of each pawl bears against indexing ring 26. Theprotrusions 32 on pawls 24 drive against teeth 34 on ring 26 and seek tomesh with them. For the pawls to expand sufficiently for an actuator topass, protrusions/teeth 32, 34 must fully mesh. When protrusions/teeth32, 34 fully mesh, the one or more pawl protrusions 32 drive intovalleys 34 a and any misalignment causes ring 26 to rotate a smallamount as each pawl protrusion 32 slides down along the flank of a toothinto the base of the valley. Ring 26 can only rotate in one direction.As soon as the actuator passes, however, pawls 24 are biased inwardly byspring 31. In addition, because teeth 36, 38 have a different profilethan teeth 34, the full meshing of protrusions/teeth 32, 34 causesmisalignment of teeth 36, 38 and once protrusions 32 come out ofengagement with teeth 34 and ring 26 then rotates to bring teeth 36, 38into proper alignment. This advances ring again a small amount, andcauses misalignment of protrusions 32 and teeth 34 such that when thepawls are expanded out again, ring 26 must be rotated again to permitalignment and full meshing of protrusions 32 and teeth 34.

Eventually, ring 26 reaches a position where it can no longer rotate toallow full meshing of protrusions 32 with teeth 34. Whenprotrusions/teeth 32, 34 are unable to fully mesh, the indexingmechanism places pawls in a final position, where they can no longerexpand. In this position, a sleeve shifting device 14 is caught in theconstriction of the inner diameter IDu. Even though sleeve shiftingdevice 14 may have the same structure and the same diameter as the oneor more actuators that have already passed through pawls 24, device 14cannot pass because pawls cannot mesh with teeth 34 and therefore cannotfully expand out of axial bore 12 a.

The indexing mechanism operation depends on the interaction of pawls 24against ring 26 and the exposure of the pawls in the sleeve's innerbore, where they can be acted upon by the actuators.

During indexing, the pawls are moved by passing actuators and theindexing ring, moves incrementally rotationally about axis x as drivenby the pawls. Rotation of indexing ring 26 counts the number ofactuators that pass. While each pawl requires only one protrusion thatmoves from one valley to a following valley between teeth on indexingring, providing a plurality of protrusions 32 on each pawl increases thedurability of the mechanism.

Knowing the degree of rotation that the ring moves through when eachactuator passes, allows the ring to be set to the desired number ofactuators to be passed before the pawls are locked into the activeposition. The pawls will lock when their protrusions are no longer ableto fully mesh with the valleys on the indexing ring and that is when theindexing ring tab 42 stops against the sleeve stop tab 44. Thus, thering can be rotated to move the tab 42 away from the stop tab a numberof incremental rotations equal to the number of actuators that are topass before the active position of the seat is reached. Effectively,this can be determined by the number of valleys on the ring throughwhich the protrusions on the pawls can move before the tab is stoppedagainst further rotation. The ring is set during assembly of the tool,as by rotating the ring to the predetermined number of actuators thatare to pass before the tool assumes the final position. The indexingring can have indicator numbers printed on its external surface 26 a andthese numbers can be lined up with a reference point, such as the stoptab, on the sleeve.

The indexing mechanism is activated to move through an indexing cyclewhen an actuator 11 moving downhole, arrow A, lands on the pawls, whichare biased into an internally constricted position by biasing spring 31to have an inner diameter between them less that the outer diameter ofthe actuator. As the actuator pushes on the pawls, the pawls rotate,arrow O, about their fulcrums 28 to open up and push on the indexingring. The indexing ring rotates when the pawls come to bear against it,due to the meshing action of the protrusions/teeth 32, 34 and therotational restriction imparted by internal toothed surface 36. When theprotrusions seek to mesh entirely, the protrusions on pawls 24 causering 26 to rotate slightly. When the pawls have opened entirely, theindexing ring is advanced by one incremental rotation and the innerdiameter ID across the pawls is equal to or greater than the outerdiameter of the actuator. The actuator 11 passes through the pawls andthe spring forces, arrow I, the pawls back into a constricted positionin bore 12 a.

After the last stage is reached, tab 42 on ring 26 stops on thecorresponding stop tap on the sleeve 12. This stops all rotation of thering 26 and locks pawls 24 in the final position, wherein they areconstricted, protruding into inner bore 12 a of the sleeve and have anunexpanded inner diameter IDu thereacross. Pawls 24 form seat 16 thatcannot expand and the sleeve is ready to be shifted open (FIGS. 3 and4B). Any sleeve shifting device 14 that passes into sleeve 12 cannotpass through pawls 24. This occurs even though sleeve shifting device 14may be identical to actuators 11. Since the pawls are locked againstexpanding, the force that would previously open the pawls is transmittedto shear pins 17 connecting the sleeve to the tubular housing 20. Thepressure applied to the ball causes the shear pins 17 to shear andsleeve 12 shifts down to the open position and can be locked into theopen position by a c-ring acting between the sleeve and the tubularhousing.

In the starting position, as the tool is run into the well, ring 26 isat the set starting position. As actuators are passed through, the ringis rotated one rotation at a time towards a position with tab 42 stoppedagainst the stop tab.

The number of times that a pawl is capable of expanding to allow anactuator to pass before arriving at the active position, where it can nolonger expand, depends on the position of the ring tab 42 relative tothe stop tab on the sleeve and, in particular, the number of times thatindexing ring can be incrementally rotated by pawls.

During wellbore operations, actuators 11 are launched from above, suchas from surface to at least drive the tool through its inactive cycles.The actuators pass through the inner bore of sleeve 12. The actuatorsmay serve other purposes in the well, if desired.

In this entire process, sleeve 12 that carries pawls 24 remains axiallyand rotationally stationary, while pawls 24 pivot and indexing ring 26moves rotationally outside of sleeve 12.

As will be appreciated, the downhole tool can include various componentsfor appropriate operations. For example, seals 60 may be positionedbetween sleeve 12 and housing 20 to prevent fluid leakage and bypass.Torque resistors, such as pins 61 in slots 62, may be employed tocontrol against rotation of the sleeve 12 about axis x.

Likewise, a mode of construction may be employed that best configuresthe parts and/or facilitates construction. For example, as noted,various parts may be formed of interconnected subcomponents.

The tool illustrated in FIGS. 1 to 4B may be employed in a method toindex a tool through a plurality of inactive positions before arrivingat an active position. For example, the indexing mechanism can be set toundergo any number of cycles up to the maximum number of incrementalrotations depending on the size of protrusions/teeth 32, 34, number ofpawls, etc. before arriving at the active position. The number of cyclesmay be selected based on the number of actuators that are intended topass through the tool prior to the tool being configured into its activeposition for its main function.

In use, one or more of the tools with an indexing mechanism may bepositioned in a tubing string. Because of their usefulness to increasethe possible numbers of sleeves in any tubing string, the sliding sleevetools may be installed above one or more sleeves having a set valveseat. For example, with reference to FIG. 5, a wellbore tubing stringapparatus may include a tubing string 614 having a long axis and aninner bore 618, a first sleeve 632 in the tubing string inner bore, thefirst sleeve being moveable along the inner bore from a first positionto a second position; a second sleeve 633 in the tubing string innerbore, the second sleeve offset from the first sleeve along the long axisof the tubing string, the second sleeve being moveable along the innerbore from a third position to a fourth position; and a third sleeve 634offset from the second sleeve and moveable along the tubular string froma fifth position to a sixth position. The first sleeve may have anindexing mechanism 638 such as according to one of the embodimentsdescribed above, including pawls and the other components of theindexing mechanism, which can be actuated to form a non-expandable valveseat (shown not yet formed). The second and third sleeves may bereconfigurable or, as shown, standard sleeves, with a set valve seat 626a, 626 b therein.

The sleeve furthest downhole, sleeve 634, includes valve seat 626 b witha diameter D1 and the sleeve thereabove has valve seat 626 a with adiameter D2. Diameter D1 is smaller than D2 and therefore sleeve 634requires the smaller ball 623 to seal thereagainst, which can easilypass through the seat of sleeve 633. Indexing mechanism 638 of sleeve632 includes a expandable seat with an inner diameter D2.

This provides that the lowest sleeve 634 can be actuated to open firstby launching ball 623 which can pass without effect through all of thesleeves 633, 632 thereabove but will land in and seal against seat 626b. Second sleeve 633 can likewise be actuated to move along tubingstring 612 by ball 636 that is sized to pass through all of the sleevesthereabove to land and seal in seat 626 a, so that pressure can be builtup thereabove. However, in the illustrated embodiment, although ball 636can pass through the sleeves thereabove, it may actuate those sleeves,for example sleeve 632, to generate valve seats thereon. For example,when ball 636 passes sleeve 632, the ball catches in actuating mechanism638 and cycles the sleeve from one notch for an inactive position to anext notch for an active position and forms a non-expandable seat. Forexample, actuating mechanism 638 on sleeve 632 includes the expandableseat with a diameter D2 and is formed to be axially moved by ball 636passing thereby cycle the indexing mechanism and create thenon-expandable seat. However, ball 636 does pass through sleeve 632 andthe ball can continue to seat 626 a.

Of course, where the first sleeve, with the configurable valve seat, ispositioned above other sleeves with valve seats formable or fixedthereon, the formation of the valve seat on the first seat should betimed or selected to avoid interference with access to the valve seatstherebelow. As such, for example, the inner diameter of any valve seatformed on the first sleeve should be sized to allow passage thereby ofactuators (i.e. plugging balls or other plugs) for the valvestherebelow. Alternately, and likely more practical, the timing of theactuation of the first sleeve to form a valve seat is delayed untilaccess to all larger diameter valve seats therebelow is no longernecessary, for example all such larger diameter valve seats have beenactuated or plugged.

In one embodiment as shown, the wellbore tubing string apparatus may beuseful for wellbore fluid treatment and may include ports 617 over orpast which sleeves 632, 633, 634 act.

In an embodiment where sleeves 632, 633, 634 are positioned to controlthe condition of ports 617, note that, as shown, in the closed portposition, the sleeves can be positioned over their ports to close theports against fluid flow therethrough. In another embodiment, the portsfor one or both sleeves may have mounted thereon a cap extending intothe tubing string inner bore and in the position permitting fluid flow,their sleeve has engaged against and opened the cap. The cap can beopened, for example, by action of the sleeve shearing the cap from itsposition over the port. Each sleeve may control the condition of one ormore ports, grouped together or spaced axially apart along a path oftravel for that sleeve along the tubing string. In yet anotherembodiment, the ports may have mounted thereover a sliding sleeve and inthe position permitting fluid flow, the first sleeve has engaged andmoved the sliding sleeve away from the first port.

The tubing string apparatus may also include outer annular packers 620to permit the creation of isolated wellbore segments between adjacentpackers. The packers can be of any desired type to seal between thewellbore and the tubing string. In one embodiment, at least one of thefirst, second and third packer is a solid body packer including multiplepacking elements. In such a packer, it is desirable that the multiplepacking elements are spaced apart.

In use, a wellbore tubing string apparatus, such as that shown in FIG. 5including tools with indexing mechanisms, for example according to oneof the various embodiments described herein, may be run into a wellboreand installed as desired. Thereafter the sleeves may be shifted to allowfluid treatment or production through the string. Generally, the lowermost sleeves are shifted first since access to them may be complicatedby the process of shifting the sleeves thereabove. In one embodiment,for example, the actuator, such as a plugging ball may be conveyed toseal against the seat of a sleeve and fluid pressure may be increased toact against the plugging ball and its seat to move the sleeve. At somepoint, any indexable sleeves are actuated to form their valve seats. Aswill be appreciated from the foregoing description, an actuator for suchpurpose may take various forms. In one embodiment, as shown in FIG. 5,the actuator is a device launched to also plug a lower sleeve or theactuator may act apart from the plugging ball for lower sleeves. Inanother embodiment, a plugging ball for a lower sleeve may actuate theformation of a valve seat on the first sleeve as it passes thereby andafter which may land and seal against the valve seat of sleeve with aset valve seat. As another alternate method, a device from below aconfigurable sleeve can actuate the sleeve as it passes upwardly throughthe well. For example, in one embodiment, a plugging ball, when it isreversed by reverse flow of fluids, can move past the first sleeve andactuate the first sleeve to form a valve seat thereon.

The method can be useful for fluid treatment in a well, wherein thesleeves operate to open or close fluid ports through the tubular. Thefluid treatment may be a process for borehole stimulation usingstimulation fluids such as one or more of acid, gelled acid, gelledwater, gelled oil, CO₂, nitrogen and any of these fluids containingproppants, such as for example, sand or bauxite. The method can beconducted in an open hole or in a cased hole. In a cased hole, thecasing may have to be perforated prior to running the tubing string intothe wellbore, in order to provide access to the formation. In an openhole, the packers may be of the type known as solid body packersincluding a solid, extrudable packing element and, in some embodiments,solid body packers include a plurality of extrudable packing elements.The methods may therefore, include setting packers about the tubularstring and introducing fluids through the tubular string.

FIGS. 6A to 6F show a method and system to allow several sliding sleevevalves to be run in a well, and to be selectively activated. The systemand method employs a tool as described herein that will shift throughseveral “inactive” shifting cycles (FIGS. 1 to 3). Once each valvepasses through all its passive cycles, it can move to an “active” state(FIG. 4). Once it shifts to the active state, the valve can be shiftedfrom closed to open position, and thereby allow fluid placement throughthe open parts from the tubing to the annulus.

FIG. 6A shows a tubing string 714 in a wellbore 712. A plurality ofpackers 720 a-f can be expanded about the tubing string to segment thewellbore into a plurality of zones where the wellbore wall is theexposed formation along the length between packers. The string may beconsidered to have a plurality of intervals 1-5, each intervalidentified as between each adjacent pair of packers. Each intervalincludes at least one port and a sliding sleeve valve thereover (withinthe string), which together are designated 716 a-e. Sliding sleeve valve716 a includes a ball stop, herein called a seat, that permits aball-actuated axial force to be applied to move the sleeve away from theports it covers. Sliding sleeve valves 716 b to 716 e each includetherein expandable seats, which are formable to non-expandable seatswhen actuated to do so by use of an indexing mechanism for movement ofthe seat between inactive positions where the seat is expandable and anactive position where the seats is activated and formed in anon-expandable manner. For example, the seats of sleeves 716 a to 716 emay be similar to seat 16 as shown in FIGS. 1 to 4, that is configurableto a ball retaining diameter upon being cycled into an active position.

Initially, as shown in FIG. 6A, all ports are in the closed position,wherein they are closed by their respective sliding sleeve valves.

As shown in FIG. 6B, a ball 736 may be pumped onto a seat in the sleeve716 a to open its port in Interval 1. A wellbore fluid treatment may beeffected through the ports opened by sleeve 716 a. When the ball passesthrough the sleeves 716 c-e in Intervals 5, 4, and 3, pawls make apassive shift to move their indexing rings one position closer to tab 42set against the stop tab of the sleeve. When the ball passes throughInterval 2, it moves the indexing mechanism to support the pawls againstpivoting and a non-expandable ball stop is formed on sleeve 716 b onthat interval such that it can be shifted to the open position whendesired.

Next, as shown in FIG. 6C, a ball 736 a is pumped onto the activatedseat in sleeve 716 b to open the port in Interval 2. When it passesthrough the sleeves in Intervals 5, and 4, they make a passive shift.When the ball passes through Interval 3, it moves sleeve 716 c from aninactive position to an active position so that it can be shifted to theopen position when desired. When ball 736 a lands in sleeve 716 b inInterval 2, it opens that sleeve by landing on the ball stop formed inFIG. 6B and a wellbore fluid treatment may be effected through the portsopened by sleeve 716 b.

Thereafter, as shown in FIG. 6D, a ball 736 b is pumped onto theactivated seat in sleeve 716 c to open the port in Interval 3. When ball736 b lands in sleeve 716 c, it opens that sleeve by landing on the ballstop formed in FIG. 6C and a wellbore fluid treatment may be effectedthrough the ports opened by sleeve 716 c. When ball 736 b passes throughthe sleeve 716 e in Interval 5, that sleeve makes a passive shift wherepawls drive the indexing ring to advance one incremental rotation closerto a position where the ring's tab 42 is stopped from further rotation.When the ball passes through Interval 4, it moves sleeve 716 d frominactive to active, for example with tab 42 set against a stop tab onthe sleeve so the indexing ring can no longer be rotated, so that sleeve716 d can be shifted to the open position when desired.

Thereafter, as shown in FIG. 6E, a ball 736 c is pumped onto theactivated seat of sleeve 716 d to open the port in Interval 4 and afluid treatment may be effect therethrough. When ball 736 c passesthrough Interval 5, it moves sleeve 716 e from inactive to active sothat it can be shifted to the open position when desired.

Thereafter, as shown in FIG. 6F, a ball 736 d is pumped onto theactivated seat of sleeve 716 e to open the port in Interval 5 completingopening of all ports.

With reference to the tool of FIGS. 1 to 4B, it is noted that sleeve 716b of Interval 2 would be installed with the indexing ring only onerotational position away from being stopped, such that after only oneactuation thereof (i.e. after one ball passes therethrough), theindexing ring would be moved to stopped position and pawls 24 are in aposition forming seat 16 in a non-expandable configuration. Likewise,the sleeve 716 c of Interval 3 would be installed with its indexing ringjust two rotations from a stopped position, such that after twoactuations thereof (i.e. after two balls pass therethrough), theindexing ring would be stopped from further movement and the pawls wouldbe locked from expanding. Thus, the seat would be activated in anon-expandable form. The other sleeves 716 d and 716 e would beinstalled with their rings rotated to provide for three and fourrotations, respectively.

When the ports are each opened, the formation accessed therethrough canbe stimulated as by fracturing. It is noted, therefore, that theformation can be treated in a focused, staged manner. It is also notedthat balls 736-736 d may all be the same size, but still this portion ofthe formation can be treated in a focused, staged manner, through oneport at a time. Note that while only five ports are shown in thissegment of the string, more than five ports can be run in a string. Theintervals need not be directly adjacent, as shown, but can be spaced andthere can be more than one port/sleeve per interval (i.e. at least twoports in one interval that open after the same number of actuations orwhich open in sequence). Further similar series of ports could beemployed above and/or below this series, which use other sized balls. Ofcourse, any sleeves below that use a different sized ball will use asmaller ball that can pass through the illustrated sleeves withoutactuating them.

This system and tool of FIGS. 6A to 6F provides a substantiallyunrestricted internal diameter along the string and allows a singlesized ball to function numerous valves. The sleeves may sense thepassing of a ball. As shown by sleeve 716 a, the system can usecombinations of solid ball seats and sleeves with indexing mechanisms.The system allows for installations of fluid placement liners of verylong length forming large numbers of separately accessible wellborezones.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to those embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein, but is to beaccorded the full scope consistent with the claims, wherein reference toan element in the singular, such as by use of the article “a” or “an” isnot intended to mean “one and only one” unless specifically so stated,but rather “one or more”. All structural and functional equivalents tothe elements of the various embodiments described throughout thedisclosure that are known or later come to be known to those of ordinaryskill in the art are intended to be encompassed by the elements of theclaims. Moreover, nothing disclosed herein is intended to be dedicatedto the public regardless of whether such disclosure is explicitlyrecited in the claims. No claim element is to be construed under theprovisions of 35 USC 112, sixth paragraph, unless the element isexpressly recited using the phrase “means for” or “step for”.

1. A wellbore tool that is actuable through a plurality of positionscomprising: a tubular housing including an upper end, a lower end, anaxis extending between the ends and a wall defined between an innersurface and an outer surface; a tool mechanism capable of beingreconfigured from a first inactive position to an active position; anindexing mechanism for reconfiguring the tool mechanism, the indexingmechanism including an indexing ring in the tubular housing, theindexing ring including an inner bore and being rotatably movable aboutthe axis, and an inner sleeve positioned within the tubular housing andextending through the inner bore, the inner sleeve having an axial boreextending therethrough and a wall thickness, and a plurality of pawlsforming a seat on the inner sleeve, each of the plurality of pawls beingpivotally connected to the inner sleeve and having an inner facingsurface open to and biased into the axial bore and a back side surfacepositioned for engagement with the indexing ring; and an actuator forpassing through the axial bore and contacting the inner facing surfacesto drive the plurality of pawls radially out into full meshingengagement with the indexing ring to thereby drive the indexing ring torotate and to move the tool mechanism from the first inactive positiontoward the active position.
 2. The wellbore tool of claim 1 wherein theindexing ring is rotatably moveable in one rotational direction onlyabout the axis.
 3. The wellbore tool of claim 1 wherein the indexingring is a gear ring with an internally toothed profile and the pluralityof pawls include at least one protrusion on the back side surface tomesh with the internally toothed profile.
 4. The wellbore tool of claim1 wherein the plurality of pawls are each pivotally connected to rotateabout a fulcrum axis substantially parallel to the axis.
 5. The wellboretool of claim 1 wherein the sleeve is retained against rotating aboutthe axis.
 6. The wellbore tool of claim 1 wherein in the activeposition, the indexing ring is stopped from rotating.
 7. The wellboretool of claim 1 wherein in the active position, the plurality of pawlsare stopped from rotation into full meshing engagement such that asleeve shifting device cannot pass through the plurality of pawls. 8.The wellbore tool of claim 1 wherein the tool mechanism is the seat andin the active position, the seat forms a non-expandable ball seat. 9.The wellbore tool of claim 6 wherein the seat in the inactive positionis expandable.
 10. A wellbore sliding sleeve sub comprising: a tubularhousing including an upper end, a lower end, an axis extending throughthe upper end and the lower end and a wall defined between an innersurface and an outer surface; a port through the wall of the tubularhousing; a sleeve in the tubular housing, the sleeve having an innerbore and being moveable from a closed position overlying the port to anopen position exposing the port; a ball seat on the sleeve configurablebetween an expandable form and non-expandable form, the ball seatincluding a plurality of pawls, each pawl having a front side surfaceexposed in the inner bore and a backside surface opposite the front sidesurface and each pawl being pivotally connected to the sleeve through afulcrum having an axis of rotation substantially parallel to the axissuch that the pawls are rotationally moveable between a constrictedposition protruding into the inner bore and an expanded position havingan inner diameter greater than the constricted position; an indexingmechanism for reconfiguring the ball seat from the inactive position tothe active position, the indexing mechanism including a pawl protrusionon the back side surface of at least one pawl and an indexing ring witha plurality of teeth on its inner facing surface, the plurality of teethforming at least one valley capable of meshing with the pawl protrusion,the indexing ring being rotatable relative to the sleeve and encirclingthe sleeve about the plurality of pawls, expansion of the plurality ofpawls from the constricted position to the expanded position drivingmeshing of the pawl protrusion with the at least one valley and rotationof the indexing ring to accommodate the meshing; and an actuator forpassing through the inner bore and contacting the front side surfaces ofthe plurality of pawls to drive the pawls to the expanded position toforce the pawl protrusion to mesh with the valley of the indexing ringand thereby to rotate the indexing ring relative to the sleeve toreconfigure the ball seat from the expandable form toward thenon-expandable form.
 11. The wellbore sliding sleeve sub of claim 10wherein misalignment between the pawl protrusion and the valley drivesrotation of the indexing ring when the pawl protrusion meshes with thevalley.
 12. The wellbore sliding sleeve sub of claim 10 wherein theindexing ring includes a number of valleys and the number of valleysdefines a number of actuators that are passable through the plurality ofpawls before the ball seat is moved to the non-expandable form.
 13. Thewellbore sliding sleeve sub of claim 10 wherein in the non-expandableform the indexing ring is stopped from rotation and the pawl protrusionis stopped from meshing.
 14. A wellbore fluid treatment stringcomprising a string and sliding sleeve sub according to claim 11, afirst annular packer on the string uphole of the sliding sleeve sub anda second annular packer on the string downhole of the sliding sleevesub, the first annular packer and the second annular packer beingexpandable to form an isolated wellbore segment therebetween.
 15. Thewellbore fluid treatment string of claim 14 further comprising asleeve-shifting device to land on the ball seat after the ball seat isconfigured into the non-expandable form.
 16. A method for actuating adownhole tool to an active position, the method comprising: passing anactuator through a expandable ball seat in the downhole tool to permitincremental movement of an indexing ring about the ball seat until theindexing ring moves to a final position wherein the ball seat is held bythe indexing ring against expanding and is capable of catching a sleeveshifting device.
 17. The method of claim 16 wherein during passing theball seat remains axially stationary in the downhole tool.
 18. Themethod of claim 16 wherein passing includes driving a plurality of pawlsthat form the ball seat from a constricting position out into fullmeshing engagement with the indexing ring as the actuator passes overthe plurality of pawls and biasing the plurality of pawls back into theconstricting position when the actuator clears the plurality of pawls.